DSI refers to the local coordinate system to translate, rotate, mirror, copy, and generate points, lines, and nodes. When such a function is selected, the program will automatically prompt the user to generate a local system designated as the UVW coordinate frame. One, two, or three reference points are required to establish a local coordinate system.
For a three-point system, the first reference point defines the local origin. The second reference, which extends from the first reference point, defines the direction of the local U-axis. The third reference point defines the local UV plane. The local W-axis is defined in the UV plane and is perpendicular to the U-axis. The local W-axis is then defined according to the right hand rule perpendicular to the UV plane.
For the two-point option, DONE should be selected after the second reference point is defined. The local W-axis lies along the vector from the origin to the second reference point, the V-axis lies in the VW plane, and the U-axis is defined by the right hand rule.
Note: All rotational commands (generating arcs, copying with rotation, etc.) are executed about the local W- or global Z-axis.
For the one reference point option, the user selects a point or node on the screen as the local origin then enters one of the X, Y, or Z options that are listed to define the local W along one of the global axes.
1. When creating a local coordinate system, DSI prompts:
> CREATE LOCAL COORDINATES
PICK NODE/PT FOR ORIGIN
• DSI prompts for a desired coordinate system (local or global) in the options area.
? ABORT
GLOBAL SYSTEM
KEY IN X, Y, Z
• This signals the user to key in the origin of the local coordinate system.
> ENTER X, Y, Z COORDINATES
• The user enters the values for the X, Y, and Z coordinates, e.g.10,0, and 0.
NODE
• Default
POINT
SHOW LAST C.S.
• Once the last coordinate system has been displayed, see step 3.
• The user may select a node or a point, enter a coordinate by keyboard, or use any combination of these options to create a local coordinate system.
2. Once a reference point has been selected, DSI prompts:
> PICK NEXT POINT OR NODE
? ABORT
DONE
• After the user selects 2 reference points, DSI displays the coordinate system and continues to step 3.
KEY IN XYZ
• The user may enter up to 3 reference points globally to define a local coordinate system.
INCREMENTAL XYZ
• The user may enter DX, DY, and DZ from the previous reference point to define a local coordinate system.
NODE
• The user may select up to 3 nodes to define a coordinate system.
POINT
• The user may select up to 3 points to define a coordinate system.
REJECT LAST
• This allows the user to deselect the last reference point during the selection process.
X AS LOCAL W AXIS
• This defines a local coordinate system that is parallel to the global axis with the local W along the global X-axis and the local origin at the first reference point.
Y AS LOCAL W AXIS
• This defines a local coordinate system that is parallel to the global axis with the local W along the global Y-axis and the local origin at the first reference point.
Z AS LOCAL W AXIS
• This defines a local coordinate system parallel to the global axis with the local W along the global Z-axis and the local origin at the first reference point.
3. Once the user defines the desired coordinate system, DSI displays it and prompts:
> ACCEPT? (Y/N/A)
? YES
• DSI prompts for the next command.
NO
• The user returns to step 1.
ABORT
• The user returns to the menu.